Marine Decking with Sandwich-Type Construction and Method of Making Same

ABSTRACT

A marine deck member and the process for forming the same are provided. The marine deck member comprises a sandwich-type composite panel made by a compression molding process. In such a process, the panel is made by subjecting a heated stack of layers of material to cold pressing in a mold. The cellular core has a 2-D array of cells, with end faces open to the respective layers or skins. The surface traction of this type of composite panel can be enhanced for marine deck applications by controlled debossing, or embossing, of the first skin while it cools in the compression mold. The debossing effect can be affected by applying pressurized gas, e.g., pressurized air, onto the outer surface of the first skin while in the compression mold. The embossing can be affected by applying vacuum pressure on the outer surface of the first skin while in the compression mold.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of U.S. application Ser. No.15/615,025, filed Jun. 6, 2017, which is (i) a continuation-in-part ofU.S. application Ser. No. 13/479,974, filed May 24, 2012, now abandoned,and (ii) a continuation-in-part of U.S. application Ser. No. 13/762,879,filed Feb. 8, 2013, now U.S. Pat. No. 9,873,488; the disclosures ofwhich are hereby incorporated in their entirety by reference herein.This application is also related to (i) U.S. application Ser. No.14/603,418, filed Jan. 23, 2015, now U.S. Pat. No. 9,567,037, (ii) U.S.application Ser. No. 13/517,877, filed Jan. 14, 2012, now abandoned,(iii) U.S. application Ser. No. 15/615,019, filed Jun. 6, 2017, now U.S.Pat. No. 11,214,035, and (iv) U.S. application Ser. No. 15/615,028,filed Jun. 6, 2017, now abandoned.

TECHNICAL FIELD

This invention relates to marine decking for use with pontoon boats,docks, rafts, swim platforms, watercraft docking stations and the like,and methods for making the same.

BACKGROUND

The surfaces of boat decks, swim platforms, docks and similar marinestructures are commonly made of fiberglass, aluminum, treated plywood,vinyl or perforated rubber. These surfaces are subjected to sunlight/heat, rain, humidity, etc. in harsh marine service environments.These materials can deteriorate and require repair or replacement overextended periods of use.

Another factor is these materials can be slippery. Prior efforts toprovide non-slip marine surfaces are found in U.S. Pat. No. 4,737,390,for Non-Slip Coating for Molded Articles, and Pub. No. US 2013/0233228,for Porous Anti-Slip Floor Covering. In U.S. Pat. No. 4,737,390 a layerof latex or latex-impregnated sheet material is adhered to moldedthermoset plastic article while curing in the mold. FIG. 4 illustratesthe application of this sheet material in a boat deck. In Pub. No. US2013/0233228 a porous anti-slip floor covering uses a layer of curledstrands placed on an underlayment.

Factors affecting the suitability of a material for marine deckapplications, in addition to the ability to withstand the environmentalfactors above, include cost, weight, strength, traction and buoyancy.

SUMMARY

The marine deck materials of the present invention utilizesandwich-type, compression-molded, composite components. Sandwich-typecomposite panels including cores have very important characteristicsbecause of their light weight and high strength. Such panels areconstructed by sandwiching a cellular core having low strengthcharacteristics between two outer plastic layers or skins, each of whichis much thinner than the core but has excellent mechanicalcharacteristics. The core is made of a 2-D array of cells, each of thecells having an axis substantially perpendicular to the outer surfacesand extending in the space between the layers or skins, with end facesopen to the respective layers or skins.

Sandwich-type composite panels are conventionally made by a compressionmolding process. In such a process, the panel is made by subjecting aheated stack of layers of material to cold pressing in a mold. The stackis made up of, at least: a first skin of plastic material, a cellularcore, and a second skin also of plastic material. The stack may bepre-heated outside the mold or heated inside the mold to a softeningtemperature. Once the stack is placed in the mold, the closing of themold halves causes the inner surfaces of the softened skins to bond tothe mating faces of the core.

In one embodiment, the sandwich-type composite panel has a first skin ofthermoplastic material, a second skin of thermoplastic material, and acellular core of thermoplastic material positioned between the skins.The skins are bonded to the core by press molding. The cellular core hasa 2-D array of cells, each of the cells having an axis substantiallyperpendicular to the outer surfaces and extending in the space betweenthe layers or skins, with end faces open to the respective layers orskins.

In another embodiment, the sandwich-type composite panel has a firstskin of a fiber-reinforced thermoplastic material, a first sheet ofthermoplastic adhesive, a second skin of fiber-reinforced thermoplasticmaterial, a second sheet of thermoplastic adhesive and a cellular coreof a cellulose-based material positioned between the skins. The skinsare bonded to the core by the first and second adhesive sheets and bypress molding. The cellular core has a 2-D array of cells, each of thecells having an axis substantially perpendicular to the outer surfacesand extending in the space between the layers or skins, with end facesopen to the respective layers or skins.

The surface traction of this type of composite panel can be enhanced formarine deck applications by controlled (i) debossing, or (ii) embossing,of the first, outer skin while it cools in the compression mold. The airin the core cavities causes thermal gradients relative to the cell wallsthat result in uneven cooling over the surface area of the skin. Theresultant uneven cooling is manifested as “debossing” (or “sink marks”)on the surfaces of the skins. The phenomenon of debossing can be usedadvantageously to enhance surface traction of the outer surface of thefirst skin.

The debossing effect can be accentuated by applying pressurized gas,e.g., pressurized nitrogen or air, onto the outer surface of the firstskin as it cools in the compression mold.

Alternatively, the uneven cooling phenomenon can be used to “emboss” thesurface of the skin be application of vacuum pressure while the skin iscooling in the mold. The embossments are raised surfaces that alsoenhance surface traction on the outer surface of the first skin.

The debossing/embossing pattern on the outer surface can be defined bythe cross-sectional shape of the cells. Cells of circularcross-sectional will produce circular debossments/embossments; cells ofhoneycomb shape will produce hexagonal debossments/embossments; andcells of cleated shape will produce cleat-shapeddebossments/embossments.

The present invention provides marine deck materials that have arelatively high strength-to-weight ratio, buoyancy, and enhanced surfacetraction. These properties make these deck materials suited for use insuch applications as boat decks, swim platforms, docks and similarmarine structures.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a pontoon deck as a representativeproduct application of the present invention;

FIG. 2A is an enlarged view of the pontoon deck surface, encircled as“2A” in FIG. 1 , showing debossments matching the cross-sectional shapeof the circular cells in the core;

FIG. 2B is an enlarged view of a pontoon deck surface showingembossments matching the cross-sectional shape of the circular cells inthe core;

FIG. 3 is a perspective view of a swim platform or diving raft asanother representative product application of the present invention;

FIG. 4 is a perspective view of a dock as another representative productapplication of the present invention;

FIGS. 5A, 5B, and 5C are top plan schematic views, partially brokenaway, of different configurations, e.g., honeycomb-like, of cellularcores;

FIG. 6 is an exploded, side sectional view showing a sandwich-typecomposite panel with a first skin of a fiber-reinforced thermoplasticmaterial, a first sheet of thermoplastic adhesive, a second skin offiber-reinforced thermoplastic material, a second sheet of thermoplasticadhesive and a cellular core of a cellulose-based material positionedbetween the skins;

FIG. 7 is an exploded, side sectional view showing a sandwich-typecomposite panel with first skin of thermoplastic material, a second skinof thermoplastic material, and a cellular core of thermoplastic materialpositioned between the skins;

FIG. 8 is a schematic, side sectional view showing a fluidpressure-assisted compression mold useful in facilitating debossing ofthe of the upper surface of the molded composite component to enhanceits surface traction;

FIG. 9 is a top perspective view, in cross section, of the compositecomponent of FIG. 6 , with debossments, by application of fluidpressure;

FIG. 10 is a schematic, side sectional view showing a vacuumpressure-assisted compression mold useful in facilitating embossing ofthe of the upper surface of the molded composite component to enhanceits surface traction;

FIG. 11 is a top perspective view, in cross section, of the compositecomponent of FIG. 6 , with embossments, by application of vacuumpressure;

FIG. 12 is a cross-sectional view, partially broken away, of a marinedeck member of the present invention having a fastener component mountedwithin.

DETAILED DESCRIPTION

As required, detailed embodiments of the present invention are disclosedherein; however, it is to be understood that the disclosed embodimentsare merely exemplary of the present invention that may be embodied invarious and alternative forms. The figures are not necessarily to scale;some features may be exaggerated or minimized to show details ofparticular components. Therefore, specific structural and functionaldetails disclosed herein are not to be interpreted as limiting, butmerely as a representative basis for teaching one skilled in the art tovariously employ the present invention.

FIG. 1 shows a pontoon boat 10 as a representative application of thepresent invention. The deck 12 can be composed of modular panels ortiles fitted to the surface configuration of the pontoon boat. The deck12 has mounted on it conventional surface cleats 14 to facilitatedocking. In addition to pontoon boat decks, the present invention isalso suited for other marine applications where enhanced surfacetraction is desired, for example, docks, diving boards, swim platforms,watercraft docking stations, and the like.

FIG. 2A is a close-up view of the encircled portion of the pontoon deck12 of FIG. 1 . The deck surface has a pattern of debossments, formedwith the assistance of pressurized gas in the process of compressionmolding the marine deck. The shape of the debossment 16 corresponds tothe cross-sectional shape of the cell in the cellular core used in thecomposite molding.

FIG. 2B is a close-up view of an alternative embodiment of a pontoondeck surface 12′ showing embossments 16′ matching the cross-sectionalshape of the circular cells in the core. The embossments 16′ are formedwith the assistance of vacuum pressure in the process of compressionmolding the marine deck.

FIG. 3 shows the marine deck surfaces of the present invention appliedwith a swim platform (or diving raft) 20. The deck 12 or 12′ can beformed with debossments or embossments, respectively, as discussedbelow.

FIG. 4 shows the marine deck surfaces of the present invention appliedwith to the deck surface of a dock 22. Again, the deck 12 or 12′ can beformed with debossments or embossments, respectively, as discussedbelow.

FIGS. 5A, 5B, and 5C show exemplary surface shapes for the debossmentsand embossments to be formed in the marine deck surface, whether awatercraft deck, swim platform, dock, or other application. FIG. 5Ashows circular shapes for debossments 16C, or circular embossments 16C′.FIG. 5B shows honeycomb shapes for debossments 16H, or honeycombembossments 1611′. FIG. 5C shows rectangular shapes for debossments 16R,or rectangular embossments 16R′. The surface shape of the debossments orembossments will correspond to the cross-sectional shape of the cells inthe core of the sandwich-type structure.

FIG. 6 is an exploded side view of the constituent parts of thecomposite panel 32 preparatory to compression molding. As shown in FIG.6 , a stack includes first and second reinforced thermoplastic skins orouter layers 24 and 26, respectively, a plastic core 30 having a largenumber of cells disposed between and bonded to plies or films or sheetsof hot-melt adhesive (i.e. thermoplastic adhesive) 28 which, in turn,are disposed between and bonded to the skins 24 and 26 by compressionmolding. The sheets 28 may be bonded to their respective skins 24 and 26prior to the press molding or are preferably bonded during the pressmolding. The thermoplastic of the sheets 28 is typically compatible withthe thermoplastic of the skins 24 and 26 so that a strong bond is formedtherebetween. One or more other plastics may also be included within theadhesive of the sheets 28 to optimize the resulting adhesive 24 and 26and their respective sheets or film layers 28 (with the core 30 layers28) are heated typically outside of a mold (i.e. in an oven) to asoftening temperature wherein the hot-melt adhesive becomes sticky ortacky. The mold is preferably a low-pressure, compression mold whichperforms a thermo-compression process on the stack of materials.

The sticky or tacky hot-melt adhesive 28 extends a small amount into theopen cells during the thermo-compression process. The skins 24 and 26are bonded to the top and bottom surfaces of the core 30 by the sheets28 to seal the cells of the core 30 to the facing surfaces of the skins24 and 26.

The step of applying the pressure compacts and reduces the thickness ofthe cellular core 30 and top and bottom surface portions of the cellularcore penetrate and extend into the film layers 28 without penetratinginto and possibly encountering any fibers located at the outer surfacesof the skins 24 and 26 thereby weakening the resulting bond.

Each of the skins 24 and 26 may be fiber reinforced. The thermoplasticof the sheets or film layers 28, and the skins 24 and 26 may bepolypropylene. Alternatively, the thermoplastic may be polycarbonate,polyimide, acrylonitrile-butadiene-styrene as well as polyethylene,polyethylene terphthalate, polybutylene terphthalate, thermoplasticpolyurethanes, polyacetal, polyphenyl sulphide, cyclo-olefin copolymers,thermotropic polyesters, and blends thereof. At least one of the skins24 or 26 may be woven skin, such as polypropylene skin. Each of theskins 24 and 26 may be reinforced with fibers, e.g., glass fibers,carbon fibers, aramid and/or natural fibers. At least one of the skins24 and 26 can advantageously be made up of woven glass fiber fabric andof a thermoplastics material.

The cellular core 30 of the FIG. 6 embodiment may be a cellulose-basedhoneycomb core. In this example, the cellular core has an open-celledstructure of the type made up of a tubular honeycomb. The axes of thecells are oriented transversely to the skins 24 and 26.

The stack of material may be pressed in a low pressure, cold-formingmold 42 shown schematically in cross-section in FIG. 8 . The mold hashalves 44 and 46, which when closed have an internal cavity for thestack. The stack is made up of the first skin 24, the adhesive layers28, the cellulose-based cellular core 30, and the second skin 26, and ispressed at a pressure lying in the range of 10×105 Pa. to 30×105 Pa. Thefirst and second skins 24 and 26, and the first and second film layers28 are preferably pre-heated to make them malleable and stretchable.Advantageously, in order to soften the first and second skins 24 and 26,and their respective film layers 28, heat is applied to a pre-assemblymade up of at least the first skin 24, the first and second film layers28, the cellular core 30, and the second film layer 26 so that, whilethe composite panel 32 is being formed in the mold, the first and secondskins 24 and 26 and the film layers 28 have a forming temperature lyingapproximately in the range of 160° C. to 200° C., and, in this example,about 180° C.

Air in the sealed cavities urges softened portions of the sheets 24 and26 and portions of the core 30 inwardly towards the cavities of the core30.

The mold 42 is formed with a pattern of fluid passageways 50, alignedwith the cell openings, to permit the application of fluid pressure ontothe surface of the first skin 24 from a fluid pressure source 48. Theapplied fluid pressure augments the tendency of the sheets to deboss inthe area above the cells. The pressure level and duration can beselected to determine the depth of the debossments 16 formed in theouter surface of the first skin 24. The debossments 16 enhance thesurface traction of the outer surface of the skin 24.

FIG. 9 shows a composite panel 52 with the debossments 16R formed inrectangular shapes. The cells in the core 30 are similarly rectangularin cross-section. The outer surface of the first skin 24 has enhancedsurface traction. The outer surface of the second skin 26 may benaturally debossed, but it will not be visible as part of a marine deckmember.

FIG. 8 is an exploded side view of the constituent parts of analternative embodiment of a composite panel 40 preparatory tocompression molding. In this embodiment, thermoplastic skins 34 and 36are bonded to a thermoplastic core 38 in sealed relation by heating tothe softening point of the plastic. The stack may be preheated or may beheated in the mold.

The core may be injection molded by the process disclosed in U.S. Pat.No. 7,919,031, titled “Method And System For Making Plastic CellularParts And Thermoplastic Composite Articles Utilizing Same,” commonlyassigned to the assignee of the present invention.

A stack whether in the embodiment of stack 32 in FIG. 6 , or the stack40 of FIG. 7 , may be formed with either debossments, per the moldconfiguration of FIG. 8 , or formed with embossments, per the moldconfiguration of FIG. 10 .

In FIG. 10 , the mold 68 includes mold halves 62 and 64 (correspondingto mold halves 44 and 46 in FIG. 8 ) and is equipped with a vacuumsource 66 to apply vacuum pressure through channels 70 to the outersurface of the plastic skin 24 while the skin is heated and formable inthe mold.

The application of sufficient vacuum pressure causes the outer surfaceof the skin 24 to the raised with embossments 16 R on the compositepanel. In this case the embossments 16R are rectangular in shape tocorrespond with the cross-sectional shape of the cells in the core 30.The outer surface of the skin 24 has enhanced surface traction due tothe embossments.

FIG. 12 shows the mounting of a fastener component 80 in the compositepanel 32. The fastener component 80 includes two parts, a fastener 80Aand a sleeve 80B. The fastener component 80 can be used to secure cleats14 to a marine deck formed of the inventive composite panel.

After compression or press molding, at least one hole 81 is formed inthe composite panel 52 such as by cutting through the first skin 24,through the core 30 right up to but not through the second skin 26. Arivet-like fastener sleeve 80B is positioned in the hole 81. Eachfastener component 80 is generally of the type shown in U.S. Pat. No.7,713,011 and 2007/0258786 (Published patent application US 2007/0258786in FIGS. 15 and 16 show a tubular body 21 that receives a fastenerincluding a head portion 44 and a shank 45) wherein the preferredfastener component is called an M4 insert, installed by use of ahydro-pneumatic tool both of which are available from Sherex FasteningSolutions LLC of New York. During installation, an outer sleeve 80B ofthe fastener component 80 is deformed, as shown in FIG. 12 .

The fastener sleeve 80B typically has a relatively large annular flange,generally included at 82, with a plurality of integrally formed lockingformations or wedges 84 circumferentially spaced about a central axis ofthe fastener sleeve 80B below the flange 82 to prevent rotary motion ofthe fastener component 80 relative to the first skin 24 afterinstallation. The wedges grip into the outer surface of the first skin24 after the fastener component 80 is attached to the first skin 24.

A fastener 80 of the type illustrated in FIG. 12 can withstand (i) largepull-out forces, (ii) large push-in forces, and large rotational forces(torque). These performance criteria must be met while preserving themechanical and aesthetic properties of the composite panel 52.Additionally, in this use environment, the underside of the compositepanel 32 must remain impervious to moisture absorption. Moistureabsorption may result in increased weight and performance degradationover a prolonged period, especially on the underside of a marine deck.

While exemplary embodiments are described above, it is not intended thatthese embodiments describe all possible forms of the present invention.Rather, the words used in the specification are words of descriptionrather than limitation, and it is understood that various changes may bemade without departing from the spirit and scope of the presentinvention. Additionally, the features of various implementingembodiments may be combined to form further embodiments of the presentinvention.

What is claimed is:
 1. A method of making marine decking comprising the steps of: heating a stack of sandwich material including first and second plastic skins and a unitary, single-material plastic core positioned between the skins, the unitary, single-material plastic core having a plurality of hollow cells that share boundary walls with each cell co-extensive with a space between the plastic skins and having a cross-sectional shape and with axes oriented transversely to the plastic skins, the plastic skins and the unitary, single-material plastic core being heated to a softening temperature of the plastic skins; providing a compression mold including panel-forming, upper and lower dies, which when closed, define a mold cavity having a shape substantially corresponding to a desired shape of the panel, wherein the upper die is formed with a pattern of fluid passageways; placing the stack on the lower die in an opened position of the mold; moving the dies toward each other until the mold is in a closed position; allowing the stack to cool in the mold cavity in the closed position until inner surfaces of the plastic skins are bonded to top and bottom surfaces of the unitary, single-material plastic core to seal the hollow cells; and applying pressurized gas at a first outer surface of the stack in the mold cavity to form debossments having a cross-sectional shape which matches the cross-sectional shape of the hollow cells, wherein a first upper surface portion of the first plastic skin is disposed below a second upper surface portion of the first plastic skin where the first plastic skin is bonded to the core after cooling to form a plurality of debossments that each extend across one of the plurality of adjacent hollow cells to which the first plastic skin is bonded, wherein the pattern of fluid passageways are aligned with openings in the hollow cells in the closed position of the mold to permit the application of pressurized gas in the areas of the first plastic skin above the openings to augment the tendency of the first plastic skin to deboss in each of the areas of the first plastic skin above the openings to form a corresponding pattern of debossments which enhance surface traction of the first outer surface of the stack.
 2. A method of manufacturing decking for a marine dock comprising the steps of: heating a stack of sandwich material including first and second reinforced thermoplastic skins, first and second thermoplastic adhesive sheets, and a cellulose-based core positioned between the skins and between the sheets, the core having a plurality of hollow cells that share boundary walls, wherein each cell is co-extensive with a space between the sheets and having an axis oriented transversely to the skins and a cross-sectional shape in a plane orthogonal to the axis, the skins and the sheets being heated to a softening temperature; providing a compression mold including upper and lower dies, which when closed, define a mold cavity, wherein the upper die is formed with a pattern of fluid passageways; placing the stack on the lower die in an opened position of the mold; moving the dies toward each other until the mold is in a closed position; allowing the heated stack to cool in the mold cavity in the closed position until inner surfaces of the skins are bonded by the thermoplastic adhesive sheets to top and bottom surfaces of the core to seal the cells of the core; and applying pressurized gas at a first outer surface of the stack in the mold cavity to form debossments having a cross-sectional shape in a plane orthogonal to the axis which matches the cross-sectional shape of the cells, wherein a first upper surface portion of the first skin is disposed below a second upper surface portion of the first skin where the first skin is bonded to the core after cooling to form a plurality of debossments that each extend across one of the plurality of adjacent cells to which the first skin is bonded, wherein the pattern of fluid passageways are aligned with openings in the cells in the closed position of the mold to permit the application of pressurized gas in areas of the first skin above the openings to augment the tendency of the first skin to deboss in each of the areas of the first skin above the openings to form a corresponding pattern of debossments which enhance surface traction of the first outer surface of the stack. 